utils.go

package main

import (
	"fmt"

	"github.com/go-gl/gl/v4.1-core/gl"
	"github.com/go-gl/glfw/v3.3/glfw"
	"github.com/go-gl/mathgl/mgl32"

	//	"github.com/go-gl/mathgl/mgl32"
	"strings"
)

func compileShader(source string, shaderType uint32) (uint32, error) {
	shader := gl.CreateShader(shaderType)

	csources, free := gl.Strs(source)
	gl.ShaderSource(shader, 1, csources, nil)
	free()
	gl.CompileShader(shader)

	var status int32
	gl.GetShaderiv(shader, gl.COMPILE_STATUS, &status)
	if status == gl.FALSE {
		var logLength int32
		gl.GetShaderiv(shader, gl.INFO_LOG_LENGTH, &logLength)

		log := strings.Repeat("\x00", int(logLength+1))
		gl.GetShaderInfoLog(shader, logLength, nil, gl.Str(log))

		return 0, fmt.Errorf("failed to compile %v: %v", source, log)
	}

	return shader, nil
}

func newProg(vertShad, fragShad string) (uint32, error) {
	vertexShader, err := compileShader(vertShad, gl.VERTEX_SHADER)
	if err != nil {
		panic(err)
	}
	fragmentShader, err := compileShader(fragShad, gl.FRAGMENT_SHADER)
	if err != nil {
		panic(err)
	}
	prog := gl.CreateProgram()
	gl.AttachShader(prog, vertexShader)
	gl.AttachShader(prog, fragmentShader)
	gl.LinkProgram(prog)
	var status int32
	gl.GetProgramiv(prog, gl.LINK_STATUS, &status)
	if status == gl.FALSE {
		var logLength int32
		gl.GetProgramiv(prog, gl.INFO_LOG_LENGTH, &logLength)

		log := strings.Repeat("\x00", int(logLength+1))
		gl.GetProgramInfoLog(prog, logLength, nil, gl.Str(log))

		return 0, fmt.Errorf("failed to link prog: %v", log)
	}

	gl.DeleteShader(vertexShader)
	gl.DeleteShader(fragmentShader)

	return prog, nil
}

func UpdateUniformMat4fv(name string, prog uint32, value *float32) {
	UniformLocation := gl.GetUniformLocation(prog, gl.Str(name+"\x00"))
	gl.UniformMatrix4fv(UniformLocation, 1, false, value)

}

func Refresh(w *glfw.Window) {
	width, height := w.GetFramebufferSize()
	gl.Viewport(0, 0, int32(width), int32(height))
	projectionMat := mgl32.Perspective(mgl32.DegToRad(90),float32(width) / float32(height), 1/viewRange, viewRange)
	UpdateUniformMat4fv("projection", program, &projectionMat[0])
	fmt.Println(float32(width) / float32(height))
}